Picture transmission systems

Abstract

In a television or other picture transmission the picture is scanned in a random or pseudo-random manner enabling picture analysis and transmission within band widths considerably smaller than with conventional sequential lexicographic scans with elimination of flicker. The random scan is obtained in the X and Y directions by employing two shift registers connected serially with random bit numbers entered into the first register. The coordinates of the scanning spot are determined by the instantaneous content in the shift registers. Similar serially connected shift registers are used at the receiver, and the random bits, which are transmitted along with the video signal, are applied to the first of them. After a short period the receiver will be in synchrony with the transmitter no matter what the original content of the registers at the receiver. Conversion to a random or pseudo-random scan may be used as a step in changing from one television standard to another.

What we claim is: 
     
       1. In a picture transmission system in which every picture element is considered to be addressable in an X-Y plane and the picture is scanned according to X and Y coordinate values specifying the address of a scanning means, means for scanning the picture in a random manner comprising an X shift register and a Y shift register connected serially, a random bit generator, means for shifting each random bit as it is received from the random bit generator into the most significant position of the X register, means to shift all previous bits in both registers one position to the right in such a way that a. the bit previously in the most significant position of the X register moves to the next most sigificant position,   b. the bit in the least significant position within the X register moves to the most significant position of the Y register,   c. the bit in the least significant position of the Y register is discarded, and   d. all other bits shift to the next position to the right, thereby becoming less significant, means to position the scanning means according to the address defined by the contents of the X and Y shift registers, means to encode the luminance values of the picture element at the position defined by the current contents of the X and Y shift registers, and means for transmitting each bit output of the random bit generator along with the said luminance values.     
     
     
       2. In a picture transmission system as claimed in claim 1, means at a receiver for separating the luminance values of picture elements from the random bit signals, an X shift register and a Y shift register connected serially, means for applying the random bits to the X shift register at the receiver in the same manner as it is applied to the X shift register at the transmitter, and shifting bits in both the X and Y registers at the receiver in the same manner as at the transmitter, a display means, means to position the tracing means of the display means according to the address defined by the current contents of the X and Y registers at the receiver, and means for displaying luminance values for the picture elements. 
     
     
       3. A picture transmission system comprising means for scanning a picture in a sequential lexicographic scan to generate a picture signal, means for converting the picture signal into digital form, means for writing the digital information into a matrix considered to be addressable in an X-Y plane, means for reading out from the matrix in a random manner comprising an X shift register and a Y shift register connected serially, a random bit generator, means for shifting each random bit as it is received from the random bit generator into the most significant position of the X register, means to shift all previous bits in both registers one position to the right in such a way that a. the bit previously in the most significant position of the X register moves to the next most significant position of the Y register,   b. the bit in the least significant position within the X register moves to the most significant position of the Y register,   c. the bit in the least significant position of the Y register is discarded, and   d. all other bits shift to the next position to the right, thereby becoming less significant, means for reading out the luminance values in digital value at the address in the matrix defined by the contents of the X and Y shift registers, means for encoding the luminance values and means for transmitting each bit output generated by the random bit generator along with the encoded luminance values.     
     
     
       4. In a picture transmission system in which every picture element is considered to be addressable in an X-Y plane and the picture is scanned according to X and Y coordinate values specifying the address of a scanning means, means for scanning the picture in a pseudo random manner comprising an X shift register and a Y shift register connected serially, a pseudo random bit generator, means for shifting each pseudo random bit as it is received from the pseudo random bit generator into the most significant position of the X register, means to shift all previous bits in both registers one position to the right in such a way that a. the bit previously in the most significant position of the X register moves to the next most significant position,   b. the bit in the least significant position within the X register moves to the most significant position of the Y register,   c. the bit in the least significant position of the Y register is discarded, and   d. all other bits shift to the next position to the right, thereby becoming less significant, means to position the scanning means according to the address defined by the contents of the X and Y shift registers, means to encode the luminance values of the picture element at the position defined by the current contents of the X and Y shift registers, and means for transmitting each bit output of the pseudo random bit generator along with the said luminance values.     
     
     
       5. In a picture transmission system as claimed in claim 4, means at a receiver for separating the luminance values of picture elements from the pseudo random bit signals, an X shift register and a Y shift register connected serially, means for applying the pseudo random bits to the X shift register at the receiver in the same manner as it is applied to the X shift register at the transmitter, and shifting bits in both the X and Y registers at the receiver in the same manner as at the transmitter, a display means, means to position the tracing means of the display means according to the address defined by the current contents of the X and Y registers at the receiver, and means for displaying luminance values for the picture elements. 
     
     
       6. A picture transmission system comprising means for scanning a picture in a sequential lexicographic scan to generate a picture signal, means for converting the picture signal into digital from, means for writing the digital information into a matrix considered to be addressable in an X-Y plane, means for reading out from the matrix in a pseudo random manner comprising an X shift register and a Y shift register connected serially, a pseudo random bit generator, means for shifting each pseudo random bit as it is received from the pseudo random bit generator into the most significant position of the X register, means to shift all previous bits in both registers one position to the right in such a way that a. the bit previously in the most significant position of the X register moves to the next most significant position of the Y register,   b. the bit in the least significant position within the X register moves to the most significant position of the Y register,   c. the bit in the least significant position of the Y register is discarded, and   d. all other bits shift to the next position to the right, thereby becoming less significant, means for reading out the luminance values in digital value at the address in the matrix defined by the contents of the X and Y shift registers, means to encode the luminance values of the picture element at the position defined by the contents of the X and Y shift registers, and means for transmitting each bit output of the pseudo random bit generator along with the encoded luminance values.